It is easy.
The iconians are behind everything, we know this.
We know sela has been taken by the iconians. They backed her before.
And we know that the voice acting for Sela si shedluded for march.
Therefore:
Sela is coming back with more iconian backing and trying to reestablish the ISE anew.
No Romulan faction to play. Maybe a cooperation of feds and kdf to combat the new threat. But that is it.